vpxenc: don't print STATS_PKT size w/--quiet

missed in 1fc3cc8

Change-Id: I80ffc1179245bc124e9938aad92a4d5fdfee187b
diff --git a/vpxenc.c b/vpxenc.c
index 7449e6c..c9547ea 100644
--- a/vpxenc.c
+++ b/vpxenc.c
@@ -2284,8 +2284,9 @@
             break;
         case VPX_CODEC_STATS_PKT:
             stream->frames_out++;
-            fprintf(stderr, " %6luS",
-                   (unsigned long)pkt->data.twopass_stats.sz);
+            if (!global->quiet)
+                fprintf(stderr, " %6luS",
+                       (unsigned long)pkt->data.twopass_stats.sz);
             stats_write(&stream->stats,
                         pkt->data.twopass_stats.buf,
                         pkt->data.twopass_stats.sz);